1. Technical Field
The present disclosure relates to LED (light emitting diode) illumination systems, and more particularly to an LED illumination system having a low energy consumption.
2. Description of Related Art
LEDs have been available since the early 1960s. Compared with the conventional light sources, such as fluorescent lamps, halogen lamps and incandescent lamps, the LEDs have a higher electro-optical conversion efficiency. Thus, nowadays LED usage has been increased in popularity in various applications, particularly, the applications needing large power consumption, in order to reduce operation cost of these applications.
Generally, an LED lamp is connected to a constant current source for obtaining electric power therefrom. During operation, the constant current source receives a PWM signal with a frequency which is between 10 KHz and 500 KHz, and outputs a constant electric current to the LED lamp according to the received PWM signal, to make the LEDs of the LED lamp always have a radiation of constant intensity during illumination thereof. Such LED lamp would still waste a large amount of power if it always maintains the constant-intensity radiation of the LEDs during the operation thereof.
It is thus desirable to provide an LED illumination system which can overcome the described limitations.